Explosive ordnance typically has a yield—for example one ton, one kiloton, one megaton—to describe its explosive capability. More specifically, yield generally describes the total energy released in a charge's, ordnance's, munition's or the like's explosion, as usually measured by the amount of TNT necessary to cause a release of the same amount of energy. While ordnance has a yield rating, it can also have an effective yield as well. A 100% effective yield would mean that all of the main charge of that particular ordnance would be detonated. In this case that yield and the effective yield would be the same. For example, if you had a 10 kiloton weapon, and that weapon had a 100% yield, then the energy of 10 kilotons of TNT would be released upon the detonation of that weapon. In contrast, if that same 10 kiloton weapon had a 50% effective yield, then the energy output would be about 5 kilotons of TNT. In essence, then, the effective yield is the actual yield of the weapon, explosive, ordnance and the like. Ordnance typically has a single yield rating, with different size munitions being chosen for a mission based on the amount of TNT required to achieve a certain desired result. This result requires the production, storage and transport of ordnance of different physical size. It is desirable to maintain the flexibility afforded by having ordnance of differing yields while reducing the number of ordnance of differing physical size. Thus it is desired to have a variably selectable yield device.